Also in an ink jet recording system, marginless printing similar to silver salt photography has been performed. In the marginless printing, the whole surface is required to be used as an image area without leaving any non-mage area (margin) at all on an outside edge portion of a recording medium. Accordingly, ink droplets are continuously ejected from a printer head, from the surface of the recording medium to the outside of the outside edge portion, thereby being able to form a proper image up to the outside edge portion of the recording medium. The principal of the marginless printing which has hitherto been performed as described above will illustrated below with reference to the attached drawings.
First, the principal of the marginless printing is schematically shown in FIGS. 1 and 2. FIG. 1 are enlarged perspective views of a substantial part schematically showing a process of the marginless printing by the ink jet recording system. FIG. 1(A) shows a state in which a leading edge portion of the recording medium is being printed, FIG. 1(B) shows a state in which a side edge portion of the recording medium is being printed, and FIG. 1(C) shows a state in which a trailing edge portion of the recording medium is being printed. FIG. 2 is a schematic side view of the substantial part showing the state of FIG. 1(A).
As shown in FIGS. 1 and 2, an ink jet recording apparatus 10 comprises a recording head 13 mounted on a carriage 14 which reciprocates along a guide shaft 12 extending in a main scanning direction (that is to say, a widthwise direction of recording paper 11; a direction of arrow B), and a platen (not shown) disposed under this recording head 13 with facing thereto. The recording paper 11 is fed by a paper feed means (not shown) in a sub-scanning direction (a direction of arrow A in FIGS. 1 and 2) between the above-mentioned recording head 13 and the above-mentioned platen.
When a leading edge portion 11a of the recording paper 11 is fed under the recording head 13, printing on the leading edge portion 11a is initiated, as shown in FIGS. 1(A) and 2. That is to say, the recording head 13 ejects ink droplets 19 toward the direction of the recording paper 11 while reciprocating along the guide shaft 12 in the main scanning direction (the direction of arrow B), thereby initiating the printing. At this time, the printing is executed without leaving any margin on the leading edge portion 11a of the recording paper 11, so that the ink droplets 19 are also ejected on the outside of the leading edge portion 11a of the recording paper 11. The ink droplets 19 ejected on the outside of the recording paper 11 are directly deposited on a capture member 30 mounted on the platen, and further penetrate into the inside of the capture member 30 to form an ink liquid capture area 31.
When the printing on the leading edge portion 11a of the recording paper 11 is terminated, the recording paper 11 is fed in the sub-scanning direction (the direction of arrow A), and the printing on a central portion of the recording paper 11 is performed. In the printing on the central portion, the printing is executed without leaving any margin on a side edge portion 11b of the recording paper 11, so that the ink droplets 19 are also ejected on the outside of the side edge portion 11b of the recording paper 11, as shown in FIG. 1(B). The ink droplets 19 thus ejected on the outside are directly deposited on the capture member 30 mounted on the platen, and captured. Further, when the printing on the central portion of the recording paper 11 is terminated, the recording paper 11 is fed in the sub-scanning direction (the direction of arrow A), and the printing on a trailing edge portion 11c of the recording paper 11 is performed. Also in the printing on the trailing edge portion 11c, the printing is executed without leaving any margin on the trailing edge portion 11c of the recording paper 11, so that the ink droplets 19 are also ejected on the outside of the trailing edge portion 11c of the recording paper 11, as shown in FIG. 1(C). The ink droplets 19 are directly deposited on the capture member 30 mounted on the platen, and captured.
As shown in FIGS. 1 and 2, in order to perform the marginless printing, the ink droplets 19 are also ejected on the outside of the recording paper. In order to prevent the ink droplets 19 ejected on the outside of the recording paper 11 from staining the back side of the recording paper 11 and the like, it is necessary to mount the capture member on the platen. An ink jet recording apparatus in which such a capture member is mounted on the platen is shown in FIGS. 3 to 5.
FIG. 3 is a perspective view showing a typical ink jet recording apparatus 10A. A case cover 1 thereof is opened, and a print mechanism portion is particularly shown. In the print mechanism portion, there are disposed a carriage 4 equipped with ink cartridges 2 and 3 and a recording head 4A, and a platen 5 in a position facing to a traveling path thereof. Further, in a position across the platen 5, there are disposed a first paper pressing roller 6 upstream from a discharge direction of recording paper, and a second paper pressing roller 7 downstream therefrom. FIG. 4 is a partial plain view of the print mechanism portion of the ink jet recording apparatus 10 shown in FIG. 3, and FIG. 5 is a partial sectional view of the print mechanism portion of the ink jet recording apparatus 10 shown in FIG. 3.
In particular, platen openings 5a, 5b and 5c are formed in parts of the platen 5, and a capture member 20 is disposed in a lower portion of the platen 5, as shown in FIGS. 4 and 5. The platen opening 5a is a window for allowing the capture member 20 to directly capture ink droplets without depositing the ink droplets on a surface of the platen 5 and without generating ink mist in printing of a leading edge portion of recording paper P, and the platen openings 5b and 5c are each a window used in printing of a side edge portion and a trailing edge portion of the recording paper P. That is to say, of the ink droplets ejected from the recording head 4A, all of the ink droplets ejected outside the recording paper P are directly captured by the capture member 20 through the platen openings 5a, 5b and 5c. The recording paper P is fed while bringing the back side thereof in contact with a surface of the platen 5, and in that case, the capture member 20 is required to be disposed at such a height that the back side of the recording paper P does not happen to come in contact with an upper surface of the capture member 20.
The capture member 20 is carried on a support member 8, as shown in FIG. 5, and further, a support member opening 8a is formed in the support member 8. A waste ink tank 9 is provided under this support member, so that an ink liquid temporarily captured by the capture member 20 is gradually introduced from the support member opening 8a to the waste ink tank 9, and absorbed and retained by an absorbing retainer usually provided in the waste ink tank 9.
In this specification, the term “lower (under)” or “upper (above)” means lower (under) or upper (above) with respect to the gravitational direction in a state in which printing is performed by a printer.
Recently, pigment inks have been employed mainly intending to improve keeping qualities of printed matter. The capture member as described above is usually formed of a porous material (for example, a urethane foam). Accordingly, particularly in the case of the pigment ink, only a solvent component penetrates into the inside, and pigment particles tend to remain on a surface of the porous capture member to accumulate. When the accumulation of the pigment particles gradually grows up on the surface of the porous capture member to form a protrusion on the platen opening, the pigment particles are adhered to the back side of the recording paper, and further, transferred from the back side of the recording paper to the surface of the platen, resulting in staining of the back side of different recording paper.
Techniques for preventing such accumulation of the pigment particles have already been proposed. For example, a technique of impregnating the above-mentioned capture member with an organic solvent has been known (patent document 1). Further, a technique of impregnating the capture member with an organic solvent selected corresponding to the kind of color of the pigment ink has also been known (patent document 2). Furthermore, a technique of using a bilayer structure of a receiving layer and a diffusion layer, or a multilayer structure of more layers as the above-mentioned capture member has also been known (patent document 3). Moreover, a technique of forming through-holes in the above-mentioned capture member to accelerate penetration has also been known (patent document 4).
Patent Document 1: JP-A-2003-191545
Patent Document 2: JP-A-2004-174978
Patent Document 3: JP-A-2003-39754
Patent Document 4: JP-A-2004-1485